# Generate doc only if Doxygen is present.
   set( PACKAGE ${PROJECT_NAME} )
   set( VERSION ${PROJECT_VERSION} )
   set( DOC_DIR ${PROJECT_SOURCE_DIR}/doc )
   set( top_srcdir ${PROJECT_SOURCE_DIR} )
   set( HAVE_DOT YES )
   find_program(DOT_EXE dot)
   if ( DOT_EXE )
      message (STATUS "dot found: ${DOT_EXE}. Installing doc in ${INSTALL_DOC_PATH}")
   else ( DOT_EXE )
      message( WARNING "Note: dot program not found in environment. If you wish to use it in doxygen, you should add its path to the variable PATH." )
      message( STATUS "disabling dot." )
      set( HAVE_DOT NO )
   endif ( DOT_EXE )
   if (NOT EXISTS ${PROJECT_SOURCE_DIR}/doc/html)
      file(MAKE_DIRECTORY ${PROJECT_SOURCE_DIR}/doc/html)
   endif (NOT EXISTS ${PROJECT_SOURCE_DIR}/doc/html)
   install(DIRECTORY ${PROJECT_SOURCE_DIR}/doc/html DESTINATION ${INSTALL_DOC_PATH})

